The octane number of zero is assigned to A. 2-methyl octane B. n-heptane C. iso-octane D. 3-methyl octane

2-methyl octane
n-heptane
iso-octane
3-methyl octane

The correct answer is: B. n-heptane

The octane number of a fuel is a measure of its antiknock quality. A fuel with a high octane number is less likely to knock in an engine. Knocking is a phenomenon that occurs when the fuel-air mixture in an engine ignites prematurely, causing a loud knocking sound. This can damage the engine and reduce its performance.

The octane number of a fuel is determined by comparing it to two reference fuels: n-heptane and iso-octane. N-heptane has an octane number of zero, while iso-octane has an octane number of 100. A fuel with an octane number of 87 is equivalent to a mixture of 87% iso-octane and 13% n-heptane.

N-heptane is a straight-chain hydrocarbon, while iso-octane is a branched-chain hydrocarbon. Branched-chain hydrocarbons are less likely to knock than straight-chain hydrocarbons. This is because the branched-chain hydrocarbons have a more stable structure, which makes it more difficult for them to ignite prematurely.

The octane number of a fuel can be improved by adding an octane booster. Octane boosters are chemicals that are added to gasoline to increase its octane number. Some common octane boosters include ethanol, methanol, and toluene.

Ethanol is a type of alcohol that is made from corn. It is a renewable resource and is less harmful to the environment than other octane boosters. Methanol is a type of alcohol that is made from natural gas. It is a more efficient octane booster than ethanol, but it is also more harmful to the environment. Toluene is a type of hydrocarbon that is made from petroleum. It is the most efficient octane booster, but it is also the most harmful to the environment.

The octane number of a fuel is an important factor to consider when choosing a fuel for your car. If you drive a high-performance car, you will need to use a fuel with a high octane number to prevent knocking. If you drive a regular car, you can use a fuel with a lower octane number.